DevTools: do not show dynamically-added stylesheets in navigator

third_party/WebKit/Source/devtools/front_end/bindings/NetworkProject.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 244 matching lines @@
     this._addUISourceCodeWithProvider(uiSourceCode, script, this._resourceMetadata(resource));
   }
 
   /**
    * @param {!Common.Event} event
    */
   _styleSheetAdded(event) {
     var header = /** @type {!SDK.CSSStyleSheetHeader} */ (event.data);
     if (header.isInline && !header.hasSourceURL && header.origin !== 'inspector')
       return;
+    if (!header.resourceURL())
+      return;
 
     var originalContentProvider = header.originalContentProvider();
     var uiSourceCode = this._createFile(originalContentProvider, SDK.ResourceTreeFrame.fromStyleSheet(header), false);
     uiSourceCode[Bindings.NetworkProject._styleSheetSymbol] = header;
     var resource = SDK.ResourceTreeModel.resourceForURL(uiSourceCode.url());
     this._addUISourceCodeWithProvider(uiSourceCode, originalContentProvider, this._resourceMetadata(resource));
   }
 
   /**
    * @param {!Common.Event} event
@@ skipping 131 matching lines @@
     return workspace.uiSourceCode(Bindings.NetworkProject.projectId(header.target(), frame, false), url);
   }
 };
 
 Bindings.NetworkProject._networkProjectSymbol = Symbol('networkProject');
 Bindings.NetworkProject._resourceSymbol = Symbol('resource');
 Bindings.NetworkProject._scriptSymbol = Symbol('script');
 Bindings.NetworkProject._styleSheetSymbol = Symbol('styleSheet');
 Bindings.NetworkProject._targetSymbol = Symbol('target');
 Bindings.NetworkProject._frameSymbol = Symbol('frame');